1. Field of the Invention
The present invention relates to power semiconductor modules and, more particularly, relates to a power semiconductor module and its attachment structure, each of which constitutes one used by being incorporated in a vehicular rotary electric machine, for example, a relay circuit and an inverter circuit for use in a rotary electric machine for a vehicular electric power steering system.
2. Description of the Related Art
As a conventional power semiconductor module, for example, one disclosed in Japanese Patent Gazette No. 4540884 (Patent Document 1) may be used. In such a module, a plurality of semiconductor devices are directly arranged on a conductive heat dissipation substrate and these are integrally formed in a resin package by transfer mold molding together with a plurality of external connection electrodes electrically connected to the semiconductor devices.
A resin package on the surface side opposite to the surface of the heat dissipation substrate on which the plurality of the semiconductor devices are arranged is thin; the heat emitted from the semiconductor devices passes through the heat dissipation substrate and then further passes through the thin resin package to be dissipated to a heat sink attached outside the power semiconductor module. Incidentally, the power semiconductor module and the heat sink are bonded via heat dissipating adhesive or the like.